Magnetoresistance effect elements and method of fabricating the same

Abstract

In an artificial superlattice magnetoresistance effect element in which two or more of magnetic thin film layers having different coercive forces are stacked with intervening of a non-magnetic film layer and resistance changes depending on directions of magnetization in adjacent magnetic thin film layers by utilizing differences in the coercive forces, an anisotropy magnetic field Hk is increased by reducing a thickness of a soft magnetic layer, anisotropy in the magnetic thin film layer is obtained by forming the magnetic thin film layer in a magnetic field to thus increase the Hk, a material having large Hk is used as a soft magnetic material for the soft magnetic layer, and further the anisotropy is obtained by reducing a pattern width into 1-30 μm to thus increase the Hk, whereby the resistance change is achieved in the neighborhood of a zero magnetic field and thus no bias mechanism is required.

What is claimed is: 
     
       1. A magnetoresistance effect element comprising a substrate and a plurality of layers of magnetic thin films and non-magnetic thin films which are stacked alternately on said substrate, adjacent ones of said magnetic thin film layers having a non-magnetic thin film layer therebetween and having different coercive forces, wherein a coercive force Hc 2  of one layer adjacent magnetic thin film layers, a coercive force Hc 3  of the other layer of said adjacent magnetic thin film layers (O<Hc 2  <Hc 3 ), and an anisotropy magnetic field Hk 2 , in a direction of a signal magnetic field which is applied to the magnetic thin film layer having said coercive force Hc 2 , satisfy an inequality: Hc 2  <Hk 2  <Hc 3 . 
     
     
       2. The magnetoresistance effect element as defined in claim 1, wherein a pattern width of said magnetoresistance effect element is of the order of 1-30 μm. 
     
     
       3. The magnetoresistance effect element as defined in claim 1, wherein each of said magnetic thin film layers is formed from at least one magnetic material selected from the group consisting of Fe, Ni, Co, Mn, Cr, Dy, Er, Nd, Tb, Tm, Ce, Gd and their alloys and compounds. 
     
     
       4. The magnetoresistance effect element as defined in claim 3, wherein said alloy or compound are selected from the group consisting of Fe--Si, Fe--Ni, Fe--Co, Fe--Gd, Ni--Fe--Co, Ni--Fe--Mo, Fe--Al--Si, Fe--Y, Fe--Mn, Cr--Sb, Co base Fe--Al, Fe--C, Mn--Sb, Ni--Mn, Co--O, Ni--O, Fe--O, Ni--F, ferrites amorphous alloys, Co--Pt, Fe--Al, Fe--C, Mn--Sb, Ni--Mn, Co--O, Ni-O, Fe-O, Ni-F and ferrites. 
     
     
       5. The magnetoresistance effect element as defined in claim 1, wherein a main component in said magnetic thin film layer having the coercive force Hc 2  is selected from the group consisting of Ni--Fe alloy, Ni--Fe--Mo alloy and an alloy thereof. 
     
     
       6. The magnetoresistance effect element as defined in claim 2, wherein a main component in the magnetic thin film layer having the coercive force Hc 2  is selected from the group consisting of Ni--Fe alloy, Ni--Fe--Mo alloy and an alloy of said Ni--Fe alloy and said Ni--Fe--Mo alloy. 
     
     
       7. The magnetoresistance effect element as defined in claim 1, wherein each of said magnetic thin film layers has a thickness of not more than 200 angstroms. 
     
     
       8. The magnetoresistance effect element as defined in claim 7, wherein a thickness of each of said magnetic thin film layers is at least 4 angstroms. 
     
     
       9. The magnetoresistance effect element as defined in claim 1, wherein each of said magnetic thin film layers has a coercive force of 0.001 Oe-10 kOe. 
     
     
       10. The magnetoresistance effect element as defined in claim 1, wherein a ratio of said coercive forces in said adjacent magnetic thin film layers is in a range of 1.2:1-100:1. 
     
     
       11. The magnetoresistance effect element as defined in claim 1, wherein a ratio of said coercive forces in said adjacent magnetic thin film layers is in a range of 5:1-50:1. 
     
     
       12. The magnetoresistance effect element as defined in claim 1, wherein a ratio of said coercive forces in said adjacent magnetic thin film layers is in a range of 8:1-20:1. 
     
     
       13. The magnetoresistance effect element as defined in claim 1, wherein said non-magnetic thin film layer is formed from at least one metallic non-magnetic material selected from the group consisting of Au, Ag, Cu, Pt, Al, Mg, Mo, Zn, Nb, Ta, V, Hf, Sb, Zr, Ga, Ti, Sn, Pb and an alloy thereof. 
     
     
       14. The magnetoresistance effect element as defined in claim 1, wherein said non-magnetic thin film layer is formed from at least one semimetallic non-magnetic material selected from the group consisting of Si, Ge, C, B and a composite material of at least one semimetallic non-magnetic material included in said group and another element. 
     
     
       15. The magnetoresistance effect element as defined in claim 1, wherein said non-magnetic thin film layer is formed from at least one non-metallic non-magnetic material selected from the group consisting of SiO 2 , SiO, SIN, Al 2  O 3 , ZnO, MgO, TiN and a composite material of a least one non-metallic non-magnetic material included in said group and another element. 
     
     
       16. The magnetoresistance effect element as defined in claim 1, wherein said non-magnetic thin film layer has a thickness of not more than 200 angstroms. 
     
     
       17. The magnetoresistance effect element as defined in claim 16, wherein a thickness of said non-magnetic thin film layer is at least 4 angstroms. 
     
     
       18. The magnetoresistance effect element as defined in claim 1, wherein said plurality of magnetic thin film layers and non-magnetic thin film layers form an artificial superlattice film, said non-magnetic thin film layers comprising Cu, one layer of an adjacent pair of magnetic thin film layers being one of a NiFe layer and a NiFeMo layer and the other layer of said adjacent pair of magnetic thin film layers being a Co layer; wherein said artificial superlattice film is deposited on said substrate through a metallic thin layer and have a composition selected from the group consisting of NiFe(8)/Cu(55)/Co(10)/Cu(55)   NiFe(10)/Cu(55)/Co(10)/Cu(55)   NiFe(15)/Cu(55)/Co(10)/Cu(55)   NiFe(25)/Cu(55)/Co(10)/Cu(55)   NiFe(20)/Cu(35)/Co(20)/Cu(35)   NiFeMo(20)/Cu(55)/Co(20)/Cu(55).     
     
     
       19. A method of fabricating a magnetoresistance effect element in which a plurality of magnetic thin film layers and a plurality of non-magnetic thin film layers are stacked alternately on a substrate, adjacent ones of said magnetic thin film layers having a non-magnetic thin film layer therebetween and having different coercive forces, said method comprising the steps of: forming said magnetic thin film layers in a magnetic field so that an easy axis in each magnetic thin film layer is perpendicular to a direction of a signal magnetic field to be applied and so that a coercive force Hc 2  of one layer of said adjacent magnetic thin film layers, a coercive force Hc 3  of the other layer of said adjacent magnetic thin film layers (0<Hc 2  <Hc 3 ), and an anisotropy magnetic field Hk 2 , in a direction of a signal magnetic field which is applied to the magnetic thin film layer having said coercive force Hc 2 , satisfy an inequality: Hc 2  <Hk 2  <Hc 3 .   
     
     
       20. The method of fabricating a magnetoresistance effect element as defined in claim 19, wherein said magnetoresistance effect element is etched into a pattern width of 1-30 μm so that a relation among said coercive forces Hc 2  and Hc 3  and said anisotropy magnetic field Hk 2  in said magnetic thin film layer having said coercive force Hc 2  satisfies an inequality: Hc 2  <Hk 2  <Hc 3 .